I usually fill up the tank with regular, which I think is 87 octane. Do I get better miles per gallon if I buy higher octane?
Maybe. I drive mostly high-mileage cars and some of them actually did get better fuel economy on 93-octane than on 87, but not all. More accurately, they all did but sometimes the gains were negligible. It may take a couple of tankfuls for the ECU to recalibrate in order for it to make any noticable difference. Keep close track of your mileage and the amount of fuel used; fill it, reset your trip odometer, and log it. The next step is calculating whether or not it is actually worthwhile by calculating your cost per mile. When gas was ~$1.35/gallon, the extra 20 cents required that MPG improve by 13% or more to be a good investment; hard to do. Now, it is currently about 7% which is much more achievable.
